Custom valved cervical cap

ABSTRACT

A non-invasive birth control device in the form of a custom-formed, valved cervical cap is disclosed. The cervical cap comprises a cup-shaped elastomeric shell substantially complementary with contiguous surface of portio vaginalis cervicis when in contact therewith and having an aperture at the apex of the shell. The aperture is covered by an elastomeric web secured to the shell and defines, together with the shell, a one-way valve means having a discharge port offset from the aperture. The cervical cap can be fabricated from a specially designed blank of a thermoplastic elastomeric material using a replica of cervix uteri as a mold.

TECHNICAL FIELD

This invention relates to contraceptive devices and means for makingsuch devices.

BACKGROUND OF THE INVENTION

Caps for cervix uteri as a birth control means have been known for along time and have been found among the artifacts of antiquity. It hasbeen reported that Aetius of Amida suggested for this purpose the use ofa pomegranate shell cut into a hollow cup, and that beeswax discsfashioned to fit over the cervix have been used in Europe.

Modern cervical caps comprise a pre-formed rubber cap that is positionedover the cervix uteri to act as a sperm barrier. Such caps aremanufactured in several sizes to accommodate the various uterine sizesnormally encountered; however, with such caps the fit for a particularindividual is inexact and necessarily a compromise. As a result, thesecaps often become dislodged during coitus and have to be removedperiodically to accommodate normal uterine discharges. Thus, such capsare inconvenient to use and have not achieved a high degree ofreliability.

Premanufactured cervical caps with valves are also known and are shownin U.S. Pat. No. 2,836,177 to Sells, U.S. Pat. No. 3,952,737 to Lipfertet al. and German Pat. No. 475,496 to Leopold. These caps also sufferfrom the aforementioned lack of stability and are subject todislodgement during use.

U.S. Pat. No. 4,007,249 to Erb describes a technique for customfabrication of a cervical cap having a valve that is inserted duringmanufacture. The manufacturing expedients disclosed in this particularpatent contemplate the painting of a liquid, polymerizable elastomericmaterial onto the cervix uteri followed by the polymerization of thepainted material or, in the alternative, the use of a mold which retainsa liquid, polymerizable elastomeric material in contact with theexocervical surface until it is polymerized.

The former expedient is impractical because the surface to which theliquid, polymerizable material is applied is wet with mucus and quiteslippery, thus the applied material would fall off the exocervicalsurface due to gravity before polymerization of the material could takeplace and, in any event, it would be impossible to control the thicknessof the applied polymerizable material during in situ polymerization. Acervical cap having a relatively non-uniform thickness is undesirable,however, because it is unstable and is likely to be dislodged in use.The second expedient disclosed in the Erb patent would also produce capshaving an undesirable variable cap thickness that is likely to bringabout dislodgement.

A further shortcoming of the caps shown in the Erb patent is that theprefabricated valving means utilized are of the leaflet or flap type. Insuch valves a viscous droplet of cervical mucus could hold the valve inan open position for an undesirably long time period, thereby providingan access aperture for sperm and defeating the very purpose of the cap.Moreover, inasmuch as the polymerizable material of the cap is in afluid state when it surrounds the prefabricated valve, some of the fluidmaterial may become enmeshed with the valve and interfere with itsintended valving action after the material has polymerized.

U.S. Pat. No. 4,007,249 to Erb also mentions a technique disclosedinitially by F. A. Wilde in 1838 in Das Weibliche Gebar-Unvermogenaccording to which a cervical cap allegedly can be made from a specialwax impression of the vaginal portion of the cervix. As recognized byErb, such a technique cannot produce an identical, negative-image,cervix-conforming inside surface because the cervix would be deformedwhile the wax impression is being made. The uterus is suspended in thelower abdomen by ligaments, is easily movable, and would tend to move upinto the abdomen even with a gentle force applied to the cervix. As aresult, accurate registration would be prevented by such a movement withattendant lack of stability for the cervical cap produced in suchmanner.

The techniques described by Erb are also likely to suffer from the samedrawback, albeit for a different reason. In particular, in practicingthese techniques the vaginal wall has to be expanded using a vaginalspeculum or similar implement in order to expose the cervix during capmolding. This expedient tends to distort the cervix as well, elongatingit along an imaginary line between the tips of the inserted, openvaginal speculum blades and shortening the cervix along an imaginaryline at right angles to the imaginary line between the tips of thespeculum blades. The attendant cervical distortion exceeds the limitsfor prosthetic stability of the cervical cap that is produced.

Accordingly, while a stable, well-fitting cervical cap can be aneffective birth-control device, heretofore it has not been possible toproduce a cervical cap that has the requisite stability againstdislodgement and that can be worn for extended periods of time such asmonths, or even years, without removal.

SUMMARY OF INVENTION

The present invention, in one aspect, contemplates a non-invasive birthcontrol device in the form of a removable cervical cap. The cap iscustom made and comprises a form-fitting apertured, elastomeric shell inwhich the aperture is situated in communication with the external os ofcervix uteri when in place and is covered with an elastomeric webconforming and secured to the shell and, together with the shell,defining a one-way valve means having a discharge port offset from theaperture.

A preferred embodiment of the cap includes a cup-shaped elastomericshell having a convex outer surface and a concave inner surface that issubstantially complementary with contiguous surface of portio vaginaliscervicis when in contact therewith. The shell defines an aperture at theapex thereof. An elastomeric web positioned over the aperture conformsand is secured to the outer surface of the shell about the aperture anddefines a pocket communicating with the aperture and providing a one-wayvalve having a discharge port for a uterine discharge while the birthcontrol device is in place. The discharge port of the valve is off-setfrom the aperture.

The shell of the cap has a depth sufficient to receive a major portionof the portio but the periphery of the shell terminates short offornices vaginae. Preferably the shell has at least a band ofsubstantially uniform rigidity circumscribing the portio and in contacttherewith. More preferably this band of substantially uniform rigidityis a band of substantially uniform shell thickness covering the entirearea of the prominent portion of the cervix surrounding the external osthereof, i.e., the cervical eminence around the external os. It is alsopreferable that the peripheral edge of the shell is feathered, i.e.,tapered or beveled from the outer surface of the shell toward the shellperiphery.

The birth control device can be conveniently formed from a blank whichis a substantially planar sheet of an elastomeric thermoplasticmaterial, preferably having a substantially uniform thickness, providedwith a central aperture. The elastomeric web, having a thickness lessthan the thickness of the planar sheet, is superposed over the apertureand is secured to the planar sheet, usually about the major portion ofthe aperture periphery, defining a pocket which provides a one-way fluidpassageway extending from the aperture, between the web and the sheet,and to a discharge port defined by the sheet and an unsealed or freeedge of the web.

The cervical cap contemplated by the present invention can be fabricatedby first making an impression of the exocervical surface of cervix uteriin the vagina in a substantially undistorted, relaxed state, making areplica of the protruding portion of cervix uteri, molding the cervicalcap utilizing the aforementioned blank, and then trimming away excessmaterial.

Yet another aspect of the present invention contemplates an implementfor making the impression of the cervix uteri which comprises, incombination, an impression tray and a syringe having an elongated nozzlereceived within said tray.

The impression tray includes a hollow cup for receiving the cervix andhaving a flexible wall that terminates in a peripheral, outwardlyflared, anterior lip. The cup is also provided with a bottom aperture. Aposterior sleeve, integral with the cup, surrounds the bottom aperture.The tray also includes a hollow, elongated stem the proximal end ofwhich is received within the posterior sleeve. The stem defines apassageway communicating with the cup interior. The length of the stemis such as to facilitate the removal of the vaginal speculum while thetray is held in place.

The syringe includes a hollow body portion, a movable plunger within thebody portion, and an elongated nozzle communicating with the hollow bodyportion and adapted to be received within the passageway defined by thehollow stem of the tray.

To make an impression of the cervix, the impression tray is positionedover the cervix with the stem protruding from the vagina. Aphysiologically tolerable, hardenable paste is dispensed from the nozzleof the syringe when inserted into the stem. The paste is distributedover the cervix and within the confines of the hollow cup of the tray.The dispensed paste is permitted to harden in situ, and thereafter thetray, containing the fixed cervical impression, is removed from thevagina. A replica of the cervix is then cast from the obtainedimpression and hardened. Thereafter the cervical cap is produced bypositioning the aforementioned blank over the replica, softening theblank by application of heat thereto, and then pressing theheat-softened blank against the replica by vacuum, air pressure, orotherwise. After the surface of the softened blank contiguous with thereplica has been deformed to assume a contour substantiallycomplementary to that of the replica, the deformed blank is cooled,removed from the replica, and trimmed to a desired size.

The valved cervical cap embodying the present invention is anon-invasive and entirely passive birth control device. The cap does notinterfere with the normal hormonal balance of the individual wearer andthus avoids the side effects commonly encountered with hormonalcontraceptives.

Inasmuch as the cap is not placed within a human body like anintrauterine device but, instead, is positioned on the exocervicalsurface of cervix uteri, it does not have to be sterilized. Likewise, noforeign body reaction and attendant rejection has been encountered.

The cap may be worn for extended periods of time, no preplanning,anticipation, or periodic attention is needed. Thus, there is nointerference with the spontaneity of sexual activity. Additionally, thepresence of the cap may protect the cervix, uterus and Fallopian tubesfrom undesirable external influences and infections.

The cap embodying this invention can be fabricated in a relatively shorttime period, of the order of about five minutes, using a replicated castof the prospective user's cervix uteri. Little technical skill isrequired for fabrication.

The one-way valve included in the present cap provides the furtheradvantages of reliability and increased sperm travel distance in theunlikely event that sperm does enter the space between the web and theshell, since the possible sperm entry region is distant from the shellaperture. The normal cyclical changes in the viscosity of cervical mucusdo not affect the efficacy or the barrier characteristics of the valve.In contradistinction to the previously known leaflet or flap-type valveswhich could be held open by a viscous droplet of cervical mucus, thepresent valve design causes droplet-like cervical mucus descending fromthe cervical os to flatten out into a very thin film, which does nothold open the valve itself.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings,

FIG. 1 is an elevational view, partly in section, of a portion of theinternal organs of the female reproductive system with a cervical capembodying the present invention in place;

FIG. 2 is an enlarged perspective view of a valved cervical capembodying the present invention;

FIG. 3 is a plan view of a blank suitable for fabricating a cervical capembodying this invention;

FIG. 4A is a sectional view taken along plane 4--4 in FIG. 3;

FIG. 4B is a sectional view similar to that in FIG. 4A but showing analternate cross-sectional configuration for the valve means in acervical cap of this invention.

FIGS. 5 and 6 illustrate devices suitable for practicing the presentinvention;

FIG. 7 is a side elevational view showing a cast replica of the cervixof female uterus; and

FIG. 8 is an enlarged sectional elevational view illustrating themanufacture of a cervical cap in accordance with the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to FIG. 1, valved cervical cap 10 is shown positioned onexocervical surface 17 of cervix uteri 11, i.e., on the portio vaginaliscervicis or that portion of uterus 13 that protrudes into vagina 12.Uterus 13 is supported by broad ligaments 14 and 15, and defines fundus16 that terminates in cervical os 18. Vaginal wall 19 and cervix 11together define the fornices vaginae, i.e., lateral fornices 20 and 21as well as the anterior and posterior fornices (not shown).

Cap 10 is a cup-shaped elastomeric shell 22 having convex outer surface23 and concave inner surface 24. Surface 26 of the portio vaginaliscervicis is not distorted by cap 10 and is in mating contact withconcave inner surface 24 at least along band 25 of shell 22 which is ofsubstantially uniform rigidity. In the area of contact, concave innersurface 24 is substantially complementary with the contiguous surface 26of the portio vaginalis cervicis. Preferably the thickness of shell 22is substantially uniform, at least along peripheral band 25, for optimumstability of cap 10 when in place. Also, it is preferred that the bandof substantially uniform thickness constitutes a major portion of shell22.

Aperture 27 is provided in elastomeric shell 22 at the apex thereof and,as shown in FIG. 1, is positioned adjacent to cervical os 18 when cap 10is in place. An external cover for aperture 27 is provided byelastomeric web 29 that is integral with shell 22. Web 29 is secured toshell 22 about a major portion of its periphery but also having anunsecured or free edge portion (FIG. 2) that together with adjacentsurface portion of convex surface 23 defines a discharge port orexternal opening 43. Web 29 lies against shell 22 and substantiallyconforms to the contour thereof. In some instances web 29 may also beunder tension and/or biased against convex surface 23. Web 29 and thecovered portion of outer surface 23 together define a pocket thatcommunicates with aperture 27 and forms a one-way valve extending fromaperture 27, between web 29 and surface 23, and defining discharge port43 in a direction away from the apex of shell 22, and thus spaced fromaperture 27. Preferably the defined discharge port is situated at leastabout one aperture diameter away from aperture 27, and more preferably,is situated near or at shell periphery 35.

This one-way valve opens under increased uterine pressure and permitsthe passage of fluids such as mucus, menstrual flow, and the like fromfundus 16 to vagina 12 without disturbing the positioning of cervicalcap 10 and without permitting the entry of sperm into fundus 16.Additionally, the precise fit of cervical cap 10 onto the portio permitsmucus to flow around it; however, at the same time the forces generatedby the flow of mucus assist in orienting and in holding cap 10 firmly inplace.

As shown in FIG. 2, optionally cap 10 can be provided with an integraltactile orientation marker 31 for the purpose of facilitatingorientation of cap 27 upon insertion, as well as enabling the wearer toperiodically assure herself that cap 10 remains properly positioned.Visual indicia 33 may also be provided on elastomeric web 29 in someinstances for the purpose of facilitating the locating of aperture 27underneath web 29 during manufacture of cap 10 as will be described indetail hereinbelow.

Shell 22 is dimensioned so as to have a depth sufficient to receive amajor portion of the portio as illustrated in FIG. 1; however, periphery35 of shell 22 terminates short of the fornices vaginae so as to guardagainst dislodgment of cap 10 during activity that may cause uterus 13to shift position and/or to deform or distend the normal configurationof the fornices. To avoid dislodgment of the cap during momentary,severe uterine displacement it is important that peripheral edge 35 issufficiently elastic to remain in contact with the exocervical surfacecontiguous therewith even during such momentary uterine displacement.For this purpose it is preferable that peripheral edge 35 be feathered,i.e., tapered or beveled as shown in FIG. 1 at 28.

Cap 10 preferably is positioned on cervix uteri 11 so that dischargeport or external opening 43 of the valve defined by web 29 inconjunction with convex outer surface 23 is located in or near theposterior fornix and also at a location on surface 23 that is closer toshell periphery 35 than to the apex of the shell. In the embodimentillustrated in FIG. 2 discharge port 43 is substantially coincidentalwith periphery 35 and preferably is situated no more than about 1 toabout 3 millimeters from periphery 35. This results in a manifoldincrease in the distance that sperm must travel to reach cervical os 18.

A portion of the increased distance for sperm travel is in vagina 12where the environment is very inhospitable to sperm motility due to therelatively low ambient pH. Usually sperm can survive in the vaginalvault only for a time period of about one to two hours. Inasmuch assperm can move at a velocity of about one to two millimeters per minute,the substantial increase in the distance that sperm must travel with cap10 in place alone markedly reduces the likelihood of fertilization.Sperm travel to cervical os 18 via the valve means in cap 10 is possibleonly in close proximity to the walls defining the valve means. Inasmuchas at least shell 22, and preferably both shell 22 and web 29 are of athermoplastic elastomeric material, which materials exhibit aninhibitory effect on sperm motility, the likelihood of sperm reachingcervix uteri 11 is further reduced.

Shell 22 can be made of a wide variety of thermoplastic elastomericmaterials, the so-called thermoplastic elastomers, such as polyolefinblends, styrene/elastomer block copolymers, copolyesters, andpolyurethane block copolymers. While these thermoplastic elastomersdiffer chemically, their morphology is similar. Blocks or domains ofrelatively hard thermoplastic constituents link elastomeric constituentsin a network that behaves like a chemically crosslinked rubberystructure. At forming temperatures the relatively hard thermoplasticdomains of the structure soften and allow the polymeric material toflow. Upon cooling, these relatively hard domains resolidify andre-establish the rubber-like, elastic structure.

Thermoplastic elastomers that exhibit a surface charge provide a furtheradvantage for the present purposes in that the presence of such a chargeon the fabricated shell and/or web tends to inhibit sperm motility.

For purposes of the present invention, the shell materials particularlysuitable are the styrene/elastomer block copolymers such as thosecommercially available from the Shell Chemical Company, Oak Brook, Ill.,under the designation "Kraton" and "Kraton G" and described in U.S. Pat.No. 3,231,635 to Holden et al. These styrenic thermoplastic elastomersare block copolymers of polystyrene and an elastomer such aspolyisoprene, polybutadiene, ethylene-propylene, or ethylene-butylenerubber.

While thermoplastic elastomeric materials of varying hardness may beused to fabricate shell 22, for optimum stability against dislodgmentpreferably the material should be harder than the cervical tissue thatcomes in contact therewith, yet the hardness should not be so high as tocause discomfort to the wearer or her consort. Preferably the shellmaterial has a Shore A durometer hardness value of about 35 to about 70,and more preferably of about 45 to about 60.

The shell material can be opaque, semitransparent or transparent;however, for ease of handling or positioning during manufacture of thecervical cap a transparent or clear material is preferred.

Web 29 can be made from the same elastomeric material or from adifferent elastomeric material, as long as web 29 can be secured toshell 22. For ease of manufacture it is preferred to have web 29 of thesame elastomeric material as the shell material but thinner. Theshell-to-web thickness ratio usually is about 7:1 to about 3:1 andpreferably about 5:1. In a typical cervical cap embodying the presentinvention the shell thickness is about 1.5 millimeters and the webthickness is about 0.3 to about 0.4 millimeters.

The relative thicknesses of the shell and the integral web in eachinstance depend on a variety of factors such as the manufacturingprocedure, forming temperatures, modulus of elasticity, and the likeconsiderations. In general, however, the web thickness is selected so asto provide a valve-opening pressure of about 10 to about 15 millimetersof mercury for the one-way valve formed by the coaction of web 29 withthe outer surface 23 of shell 22 contiguous therewith.

The material for web 29 need not be thermoplastic as long as it exhibitsthe desired elasticity and can be secured to shell 22. Not only heatsealing or ultrasonic bonding but other bonding means, e.g., adhesivebonding, can be utilized as well. In addition to the aforementionedthermoplastic elastomers, the web portion of the present valved cervicalcap can be made from materials such as natural rubber, silicone rubber,polyurethanes, fluorocarbon rubbers, styrene-butadiene rubbers, and thelike.

Valved cervical cap 10 can be fabricated by molding a blank of the typeshown in FIGS. 3 and 4A wherein blank 37 comprises substantially planarsheet 39 of elastomeric material. Aperture 27 in the central region ofsheet 39 is covered by elastomeric web 29. The contour of web 29 is notcritical and can be generally fan-like, bell-shaped, trapezoidal, orcircular, for example, as long as the web substantially conforms to themolded shell after the cap has been fabricated.

Web 29, in turn, is secured to sheet 39, e.g., by bonding peripheralregion 41 thereof. The securement of web 29 to sheet 39, and thusultimately to cap 10, is sufficient to permanently attach web 29 tosheet 39 but provides an unsealed, i.e., free, edge portion which servesto define, in part, external valve opening or discharge port 43. Inessence, web 29, when secured to sheet 39, defines a pocket or pocketscommunicating with underlying aperture 27 and provides a one-waypassageway or channel between web 29 and that portion of sheet 39 whichultimately becomes a web-covered portion of the convex outer surface 23for cap 10, terminating in discharge port 43 that is situated at leastone aperture diameter away from aperture 27. Preferably thecross-sectional area of the defined passageway increases with increasingdistance from aperture 27 as measured along convex surface 23 of shell22. Thus, in case of a trapezoidal web, for instance as shown in FIG. 3,the relatively shorter of the two substantially parallel sides of thetrapezoid is positioned nearer to aperture 27 than the relatively longerparallel side, and bonded peripheral region 41 extends about the majorportion of the periphery of aperture 27. The diameter of aperture 27 isusually about 5 to about 10 millimeters.

Aperture 27 can be a through-aperture with rectangular edges, ifdesired. However, during fabrication, a relatively thin, thermoplastic,elastomeric web may be drawn or forced into aperture 27 too far and maybe excessively deformed or even perforated at the line of contact with arectangular, sharp edge defining aperture 27. The use of such relativelythin webs, if desired, is facilitated if the aperture-defining edgeportion adjacent to web 29 is beveled as at 45 in FIG. 4A or rounded asat 47 in FIG. 1. In this manner the likelihood that web 29 may beperforated or unduly distorted during fabrication is reduced. Tactileorientation marker 31 is positioned adjacent to a sealed juncture of web29 and sheet 39.

An alternate, suitable one-way valve configuration utilizing arelatively thin web is illustrated in FIG. 4B. In this particularembodiment, aperture 44 in thermoplastic elastomeric sheet 42 is coveredby web 49 having unitary protuberance 48 extending into aperture 44 andcontacting beveled surface 46, i.e., the web 49 is thicker in the regionof aperture 44. When a custom, valved cervical cap is fabricated using acap blank of the type shown in FIG. 4B, protuberance 48 will abutbeveled surface 46 and thus will prevent excessive deformation of theweb itself during fabrication.

It should be noted, however, that even in the case of a substantiallyuniformly thick web some deformation into the shell aperture, such asaperture 27 (FIGS. 1, 3 and 8), is not objectionable as long as webintegrity is not impaired. Such deformation, as best seen in FIG. 8,also can provide a unitary protuberance that projects into the apertureand enhances the valving action. In addition, the web may be relativelythicker in the region overlying the aperture.

In some instances, particularly when sheet 39 is relatively thick, e.g.,of the order of about 2.5 millimeters or more, it is desirable to extendbevel 45 on the aperture edge portion substantially to the juncture 41of sheet 39 and web 29 so as to provide a substantially uniformthickness throughout. Alternatively, or in addition, the regionsurrounding aperture 27 and covered by web 29, in the region betweenjuncture 41 and aperture 27 may be countersunk or thinned out for thesame purpose.

A prefabricated blank of the type described offers the substantialadvantages of ease of custom cap fabrication by a practitionerassociated with the practicing physician or with a medical laboratory.

For optimum fit, concave inner surface 24 of cap 22 is substantiallycomplementary with the surface of the portio vaginalis cerviciscontiguous therewith. While it is desirable that concave inner surface24 projects slightly toward cervical os 18 about the periphery ofaperture 27, i.e., has local convexity in the aperture regioncomplementary to the concavity of the cervix in the region surroundingcervical os 18, no portion of surface 24 enters cervical os 18. To thisend, the cervix in its normal, undistorted configuration is firstreplicated as a rigid mold, e.g., in plaster, and the obtained replicais then utilized to mold the cervical cap.

Initially an impression of cervix uteri is made using a physiologicallytolerable, hardenable paste. Suitable for this purpose is an aqueouspaste made from dental impression powder, e.g., using an alginderivative, usually an alginate such as sodium alginate.

The cervical impression can be made utilizing the implements shown inFIGS. 5 and 6. Syringe 50, shown in FIG. 5, includes hollow body portion52 having an open end 53 and opposed dispensing end 54 that terminatesinto elongated nozzle 56 in communication with hollow body portion 52.Plunger 55 is positioned within hollow body portion 52 and is adapted todispense the syringe contents through nozzle 56. Impression paste 57,e.g., aqueous alginate paste, is contained within hollow body portion52. To facilitate the distribution of impression paste 57 over thecervix during the course of making the impression, it is preferable tohave a nozzle the distal end 59 of which is offset from the longitudinalaxis of the nozzle itself. In this manner nozzle discharge port 61 issituated in a plane that is at an acute angle, preferably at an angle ofabout 45 degrees, with respect to the longitudinal axis of nozzle 56,and can dispense impression paste 57 laterally over the cervix in alldirections by simply rotating syringe 50. In an alternate manner, nozzle56 can be rotatably mounted on syringe body 52 by means ofnozzle-bearing hub 62 that is rotatable with respect to syringe body 52.

Preparatory to making a cervical impression as contemplated by thepresent invention, vagina 12 is expanded using a vaginal speculum so asto expose the cervix. Thereafter impression tray 65 (FIG. 6) is insertedthrough the speculum and into the vagina, and positioned so that hollowcup 67 thereof envelops the cervix. Cup 67 has a flexible, preferablytransparent, wall 68 made from an elastomeric material such as siliconerubber, polyurethane, or the like, that terminates in a peripheral,outwardly flared, anterior lip 69 the purpose of which is to keep outadjacent vaginal wall. Wall 68 and lip 69 are also designed so as totrap the cervix and to prevent its upward rotation with attendantclosure of the anterior fornix space when the patient is in a supineposition while the cervical impression is made.

Flexible wall 68 is further provided with a plurality of spacedperforations such as perforation 66. Cup 67 at the bottom thereof isprovided with a bottom aperture surrounded by posterior sleeve 70.Proximal end 71 of hollow, elongated stem 72 is received within sleeve70. Stem 72 defines a passageway that communicates with the interior ofcup 67. A pair of opposed mounting notches, such as notch 73, areprovided in distal end 74 of stem 72. Also at or near distal end 74marker means 75 is provided on stem 72 for indicating a preselectedorientation of cup 67.

While cup 67 and stem 72 can be coaxial, for ease of manipulation andinsertion during the making of a cervical impression, and also tofacilitate the entrapment of the cervix, it is preferred that thelongitudinal axes of cup 67 and stem 72 intersect at an included angleof about 15 to about 25 degrees, and more preferably about 20 degrees.

To make a cervical impression once tray 65 is appropriately positionedenveloping the cervix, nozzle 56 is inserted through hollow stem 72.Preferably, length of nozzle 66 is selected so as to extend forsubstantially the length of stem 72. More preferably distal end 59projects into cup 67 through the bottom aperture thereof but remainsspaced from the cervix. Hub 62 (FIG. 5) on syringe, upon abutting openend 77 of stem 72, provides a positive stop that prevents nozzleaperture 61 from coming in contact with the cervix. In instances wherenozzle 56 is longer than stem 72, appropriate stop means can be providedon nozzle 56 itself or within stem 72 at the proximal end 71 receivedwithin sleeve 71.

Impression paste 57 is then dispensed from syringe 50 and distributed soas to cover the cervix, and speculum is removed from the vagina withoutremoving tray 65, and the paste permitted to set. The length of stem 72is selected long enough to permit the easy removal of the speculumwithout disturbing the position of tray 65. As the impression pastefills cup 67, minor amounts of the paste exude through perforations 66and, upon setting, anchor the formed impression within tray 65.

After the paste has set, usually within about 90 seconds, tray 65together with the cervical impression contained therewithin is liftedfrom the cervix and placed onto vibrating table 78 for casting a replicaof the cervix.

The casting operation entails pouring a slurry of plaster of Paris, orlike casting material, into tray 65 while the latter is vibrated topermit any trapped air to rise to the surface and to assure that eachand every crevice of the formed impression is filled with the slurry.After the slurry has hardened, replica 80 (FIG. 7) is removed from tray65 and is ready for use in fabricating cervical cap 10.

To this end vacuum molding techniques, e.g., drape forming, can bereadily utilized; however, any other molding technique can be utilizedas long as the material to be molded can be made to conform closely tothe cervical replica, for example, by means of positive air pressure.For purposes of illustration a preferred vacuum molding technique willbe described in detail hereinbelow.

Referring to FIG. 8, vacuum molding apparatus 82 comprises base 83 thatsupports foraminous plate 84 and heat source 86, e.g., a calrod heatingelement or infrared lamp, in a spaced relationship relative to plate 84.Alternatively, heat can be supplied by a stream of hot air. In the caseof a radiant heat source, such as an infrared lamp, the heat-radiatingsurfaces can be contoured so as to provide a substantially uniformdistance between the heat source and the blank portion nearest thereto.Channel 85 in base 83 communicates with a vacuum source (not shown) andpermits vacuum to be drawn through plate 84.

Replica 80 is positioned on plate 84 and blank 37 positioned thereoverso that visual indicia 33 is superposed over cervical os region 81 ofreplica 80. A release agent, e.g., an aerosol spray of lecithincommercially available under the designation "Pam" from Boyle-Midway,Inc., New York, N.Y. 10017, is applied to the exposed surface of blank37, and between the web and the underlying sheet and the blank is thencovered with thin protective sheet 88, e.g., a polyethyleneterephthalate film, or the like. Preferably sheet 88 is perforated inorder to facilitate the vacuum forming operation. Heat source 85 is thenturned on and heat applied to sheet 37 until it begins to soften andconform to replica 80 by its own weight. Thereafter the vacuum source isturned on and vacuum drawn through foraminous plate 84 so as to presssoftened sheet firmly against replica 80. Heat source 86 is then turnedoff or removed, and the formed sheet is permitted to cool while vacuumis maintained. Once cooled to a permanent contour, sheet 37 is removedfrom replica 80, and the formed cervical cap is excised therefrom andtrimmed to the desired shell depth. The specific shell depth in eachinstance will depend on the contour of the portio vaginalis cervicis ina given case; however, the shell peripheral edge, i.e., periphery 35,should not extend into the fornices vaginae. The feathering or bevelingof shell periphery 35 is usually done during the final trimmingoperation.

Valved cervical caps embodying the present invention, made fromstyrene/elastomer block copolymers, and having the general configurationshown in FIG. 2 have been satisfactorily worn by sexually-active femalevolunteers for a cumulative time period in excess of 290 months.

The foregoing disclosure and the accompanying drawings are intended asillustrative and are not to be construed as limiting. Still othervariations within the spirit and scope of the present invention asdefined by the claims are possible and will readily present themselvesto those skilled in the art.

We claim:
 1. A blank for a removable cervical cap which comprisesasubstantially planar sheet of a thermoplastic elastomeric materialhaving a central aperture; and an elastomeric web superposed over saidaperture and secured to the planar sheet; said elastomer web having athickness less than the thickness of said sheet and being secured tosaid sheet about the major portion of the aperture periphery butproviding a one-way passageway extending from said aperture and betweenthe web and said sheet to a discharge port defined by the sheet and afree edge of the web and offset at least one aperture diameter away fromsaid aperture.
 2. The blank in accordance with claim 1 wherein saidelastomeric web is of the same material as said sheet.
 3. The blank inaccordance with claim 1 wherein internal edge of said planar sheetdefining said aperture is beveled on the side adjacent to said web. 4.The blank in accordance with claim 1 wherein a tactile marker means isprovided on said planar sheet adjacent to the juncture of said web andsaid sheet.
 5. The blank in accordance with claim 1 wherein said planarsheet and said elastomeric web are made of styrene/elastomer blockcopolymers.
 6. The blank in accordance with claim 1 wherein said sheethas a Shore A durometer hardness value of about 35 to about
 70. 7. Theblank in accordance with claim 6 wherein said sheet has a Shore Adurometer hardness value of about 45 to about
 60. 8. The blank inaccordance with claim 1 wherein said sheet is substantially transparent.9. The blank in accordance with claim 1 wherein the sum of thethicknesses of said sheet and said web in the blank region covered bysaid web is substantially the same as the thickness of said sheet in theblank region not covered by said web.
 10. The blank in accordance withclaim 1 wherein said thermoplastic elastomeric material inhibits spermmotility.
 11. The blank in accordance with claim 1 wherein the thicknessratio of said sheet to said web is about 5:1, respectively.
 12. Theblank in accordance with claim 11 wherein said sheet is about 1.5 toabout 2 millimeters thick.
 13. The blank in accordance with claim 1wherein said web is provided with a marker indicating location of saidaperture.
 14. The blank in accordance with claim 1 wherein said web isprovided with a unitary protuberance that extends into said aperture.15. The blank in accordance with claim 1 wherein said web is thicker inthe region of said aperture.